"Three Australian environmental activists were detained on board a Japanese whaling ship on Sunday after boarding in protest at Japan's annual whale cull in the Antarctic, anti-whaling group Sea Shepherd said.

The three activists from Forest Rescue, an Australian group specializing in direct action to prevent logging, boarded the ship early on Sunday with assistance from the Sea Shepherd Conservation Society, Sea Shepherd said in a statement.

U.S.-based Sea Shepherd is tailing Japan's whaling fleet as it heads towards the Southern Ocean to try to prevent the cull.

The statement described the activists as 'prisoners now detained on a Japanese whaler.'"